I will gladly address you as an attack helicopter

The issue of gender – and how many there are – has been gaining notice over the last several years.  Take this Time article or the less respectful “I identify as an attack helicopter” copypasta.
The issue…confuses me.
Not because of the gender thing.  I mean, I know the difference between sex (biology) and gender (identification). And I also know that even the biology bit is really a lot more complicated than we like to pretend that it is.
What confuses me are the problems that people tend to have.
I mean, I had problems when people would say “that squicks me out” about homosexual relationships. My response was typically along the lines of “I don’t want to think about most hetero people having sex, so it’s all the same to me”.
Likewise when we talk about what gender identification someone wants to have. To me, it’s so simple that people’s issues with it are puzzling.

I approach this the same way I do nicknames or preferred versions of names.

If you care about someone, you’ll ask if they prefer (say) Steve or Steven, and then stick with that.  Such a request (and one that’s very individual) is seen as no big deal, and if you insist on using the wrong name (or version of a name), you are rightly seen as an inconsiderate ass.

But somehow, the same people who gladly ask which version of “Steven” I prefer will say it’s a huge imposition if a person requests to be referred to by a specific pronoun.

Put that way, it’s clear that the problem is not about confusion or difficulty.  The “problem” is with the person making the objection, not the person making the request.
Putting it in that context illustrates how deliberate the choice is.  
Related: After watching it again, I continue to highly recommend Southern Comfort (Wikipedia, YouTube) to everyone.  This 2001 documentary is… just freaking amazing.